Parking aid for a vehicle

ABSTRACT

A method for providing parking aid for a vehicle, comprises the steps recording ambient data in the external area of a vehicle, calculation of the dimensions of a specific area using the recorded ambient data, and evaluation of the suitability of the specific area as a parking space taking into account the calculated dimensions and known, vehicle-specific reference values. According to the invention, the recording of ambient data comprises recording three-dimensional images of the surroundings by means of an optical 3-D system.

INTRODUCTION

The present invention relates to a parking aid for a vehicle. In orderto facilitate driving the motor vehicle and to prevent collisions withvehicles or other objects in the way it is known to provide sensors onthe front and/or rear of the motor vehicle, which sensors emit, forexample, ultrasonic signals or radar signals and receive again thesignals which have been reflected by the obstacle. The distance betweenthe sensor which is arranged on the motor vehicle and the obstacle isdetermined here from the propagation time of the signal from the sensorto the obstacle and back again. Such a system is known, for example,from EP-A-0 984 300. Such systems are capable of transmittinginformation about the distance from an obstacle arranged behind thevehicle to the driver, for example when the vehicle is reset. However,such systems cannot provide any help in estimating the suitability of aparking space before the vehicle drives into it.

The German patent application DE-A-38 44 340 describes a device fordetermining the dimensions of a parking space. The device which isproposed in this document comprises a plurality of sensors (ultrasonic,infrared or microwave transmitters and receivers) which are mounted onthe motor vehicle and which survey the geometric position of the parkingspace with respect to the motor vehicle. The dimensions of the parkingspace are determined by trigonometric calculation methods or bydifferences in propagation time between the optical or audible signals.

The document DE-A-100 45 616 describes a method for automaticallyparking a vehicle in which the surrounding area to the front andlaterally to the front of the vehicle is recorded by means of a videocamera. This recorded real image is converted into a plan view by meansof suitable evaluation methods and said plan view is presented to thedriver on a screen. The driver can then use this plan view to detect aparking space at an early point and select it for parking. A controlsystem of the vehicle then causes the vehicle to be moved into aninitial position which is optimum for the automatic parking and theparking process can occur in a known fashion with the aid of distancesensors. A problem with this device is that the image which is recordedby the video camera has to be analyzed using complex image processingmethods in order to obtain depth information relating to the freeparking space. In order to obtain reliable depth information about theavailable free depth of the parking space, the recorded image must infact be separated computationally into an image foreground which is ofinterest and an image background which is not relevant. This processingof the recorded images is, however, very intensive in terms of computingand accordingly requires correspondingly more expensive hardwareequipment of the system.

OBJECT OF THE INVENTION

The object of the present invention is consequently to propose a bettermethod for providing parking aid and a corresponding device.

GENERAL DESCRIPTION OF THE INVENTION

This object is achieved according to the invention by means of a methodas claimed in claim 1 and a device as claimed in claim 10 of the presentapplication.

A method for providing parking aid for a vehicle, comprises the stepsrecording ambient data in the external area of a vehicle, calculatingthe dimensions of a specific area using the recorded ambient data, andevaluating the suitability of the specific area as a parking spacetaking into account the calculated dimensions and known,vehicle-specific reference values. According to the invention, therecording of ambient data comprises recording three-dimensional imagesof the surroundings by means of an optical 3-D system.

Accordingly, a device for providing parking aid for a vehicle comprisesa sensor device for recording ambient data in the external area of avehicle, and an evaluation device for calculating the dimensions of aspecific area on the basis of the recorded ambient data and forevaluating the suitability of the specific area as a parking space onthe basis of the calculated dimensions and known, vehicle-specificreference values. According to the present invention, such a system isdistinguished by the fact that the sensor device comprises an optical3-D sensor system for recording three-dimensional images of thesurroundings.

An optical three-dimensional system such as, for example, a 3-D camera,supplies both a two-dimensional image of the surrounding area and at thesame time depth information about the recorded image. The depthinformation is determined, for example, with a propagation time method,with the time period between the emission of a light pulse and thearrival of a reflected light pulse being determined and converted into adistance between the sensor system and the reflective object.Accordingly, such a system directly supplies all the necessary data forevaluating the dimensions of the space which is available for parking.It is therefore possible to eliminate the need for complex processingfor the purpose of detection and, if appropriate, for eliminating adestructive background. In fact, with the 3-D sensor system a backgroundwhich is not of interest is eliminated directly by restricting the depthof the external area of the vehicle which is to be recorded during theactual recording of the ambient data. As a result, the computationalcomplexity for evaluating the image is considerably reduced so that asystem which operates according to the proposed method requirescomparatively modest and accordingly favorable hardware equipment.

In one possible refinement of the method, the recording of ambient datacomprises recording a situation image of the entire area of interest,i.e. a possible parking space is recorded completely by the optical 3-Dsensor system. This method can be carried out either while the vehiclepasses by the potential parking space or from the stationary vehiclewhen the latter stops, for example, in the direct vicinity of thepotential parking space. For such close range observation, which may becarried out, for example, by means of a wide angle lens, a single imagerecording is sufficient in order to register all the relevant propertiesof the potential parking space. The optical 3-D sensor comprises a largenumber of pixels, each of which detects the distance from possibleobjects in its field of vision. As a result, the sensor directlysupplies topographical information about the external area of thevehicle within the measuring range. The evaluation of images canconsequently be restricted to the evaluation of an individual situationimage with this method, as a result of which the processing complexityfor the evaluation of images is minimized.

In another embodiment of the method, the recording of ambient datacomprises the successive recording of adjacent component images of thearea of interest, i.e. the area of interest is scanned by the 3-D sensorsystem. In this embodiment, the area of interest is divided into aplurality of narrow component areas which are successively recorded bythe sensor system and then evaluated together in order to determine thedimensions of the parking space. Since the individual component imagescontain comparatively less information, in contrast to an entiresituation image of the parking space, in this embodiment of the methodthe number of pixels of the sensor system can be reduced without theoverall resolution of the device being degraded. This means that thesensor system is correspondingly more cost effective. When a sensorsystem with a large number of pixels is used, it is alternativelypossible to increase the resolution of the system with such a method sothat possible obstacles are detected better.

It is to be noted that with the proposed variant of the method accordingto the invention each component image generally contains all the depthinformation related to the recorded component area. In order todetermine the length of the potential parking space, it is necessary, inaddition to the recorded component images, to determine the scanningspeed in order to be able to create a topographical image of thespecific area. The proposed embodiment of the method is used, forexample, while the vehicle drives past the potential parking space withthe instantaneous velocity of the vehicle being determined as it drivespast and being taken into account as a scanning speed during theevaluation of the individual component images. The individual,successively recorded component images of the area of interest can thenbe correlated with one another by means of a determined Vehiclevelocity. Alternatively, the 3-D sensor system can be arranged in apivotable fashion so that the area of interest can be scanned bypivoting the sensor system even on a stationary vehicle.

As has already been described above, an optical 3-D sensor system ishighly suitable for determining the dimensions of a specific area on thebasis of the directly determined distance data from individual imageinformation items. Furthermore, each obstacle which is located withinthe measuring range of the sensor system can be located with highaccuracy using the distance information which is also supplied. In anadvantageous embodiment of the invention, the latter property is used inorder to detect an obstacle in the specific area on the basis of therecorded surroundings. In this context it is even possible, by means ofa suitable configuration of the sensor system, to determine whether theobstacle is an immobile obstacle, which generally rules out using thespecific area as a parking space, or whether the obstacle is mobile,which does not necessarily rule out the use as a parking space.

By means of the determined dimensions of the potential parking space andknown, vehicle-specific reference values it is possible for theevaluation unit to evaluate whether the vehicle fits into the potentialparking space. If this evaluation is carried out, the result thereof canbe signaled to the driver of the vehicle as an instruction to attemptthe parking operation or abort it and drive to another parking space.For this purpose, the evaluation device is preferably coupled to aninformation system for outputting a result of the evaluation step to adriver of the vehicle. The result can be output, for example, opticallyon a screen which is arranged in the passenger compartment of thevehicle. Alternatively or additionally, the result can be displayedoptically by means of flashing signal lights on the dashboard and/orconveyed audibly as a signal tone or as a voice output and/ormechanically, for example by vibration of the steering wheel.

It is to be noted that the position of a parking space With respect tothe Vehicle can be determined using the recorded ambient data. Thisdetermination of position can be carried out at low cost in addition tothe calculation of the dimensions of the specific area. If theevaluation device is coupled to a control system for an automaticparking system (sensor fusion), the determined dimension and positiondata can be transmitted to this control system and used for theautomatic parking process.

In one preferred embodiment, the sensor device operates in the infraredrange. The optical 3-D sensor system then advantageously comprises apulsed infrared lighting source and an image sensor which is sensitivein the infrared range, for the purpose of recording the light pulseswhich are reflected in the external area of the vehicle.

It is to be noted that the optical 3-D sensor system is preferablymounted on the vehicle, in the external area of the vehicle. A suitableposition on the vehicle is, for example, the exterior mirror on thefront seat passenger side of the vehicle. Alternatively, the sensorsystem can be arranged in the vehicle in such a way that it looksoutward. Possible installation locations are, for example, mudguards orA, B or C pillars of the vehicle. The sensor system or the entireparking aid system can preferably be activated by the driver whennecessary with the system possibly being active only under apredetermined limiting velocity.

DETAILED DESCRIPTION WITH REFERENCE TO THE FIGURES

An embodiment of the invention will be described below with reference tothe appended figures, in which:

FIG. 1: is a schematic plan view of a possible parking situation for apassenger vehicle;

FIG. 2: is a schematic illustration of the algorithm of a propagationtime method (Time of Flight);

FIG. 3: is a block diagram of a 3-D sensor system.

The object of the present invention is to detect free parking spaceswhich are suitable for the vehicle on which the system is mounted. Thedetection can take place either on a stationary vehicle or on a vehiclewhich is driving by.

FIG. 1 shows a typical parking situation. The vehicle 2 drives along aroad. The edge of the road is bounded by vertical obstacles 4, forexample trees on a sidewalk. Two further vehicles 3 are parked along thesidewalk and a parking space 1 can be seen between said vehicles 3.

The driver of vehicle 2 would like to use this parking space. To dothis, he must firstly estimate whether the dimensions of the parkingspace 1 are sufficient to permit the vehicle 2 to be parked, of coursewithout touching the vehicles 3. This evaluation of the parking space ispreferably carried out according to a method corresponding to thepresent invention.

In the illustrated embodiment of the method, the dimensions of theparking space are determined while the vehicle 2 is driving past theparking space 1. To do this, an optical 3-D sensor system which isarranged on a front-passenger-seat-side external area, for example onthe exterior mirror 7, of the vehicle records in succession variousadjacent component images of the parking space. Each of the componentimages comprises all the topographical information from the respectivelyrecorded, narrow area 5 of the parking space 1. This means that theparking space 1 is scanned by the 3-D sensor system as the vehicle 2drives past. Each of the component images can be evaluated separatelyper se in order to detect a possible obstacle in the respectivecomponent area of the parking space. The length of the available parkingspace 1 can be determined by reference to the vehicle velocity, and ifappropriate, the scanning frequency of the 3-D sensor system bycalculating the driving distance between two component areas in which anobstacle has been detected. It is to be noted that the individualcomponent images can also be combined to form one composite image of theparking space if this were to be necessary for further image evaluation.

The depth of the measuring range 5 is preferably set in such a way thatthe 3-D sensor system processes only the information which is necessaryfor determining the dimensions of the parking space. In the embodimentshown, the depth is set, for example, in such a way that the measuringrange extends only insignificantly beyond a rear boundary, for examplethe edge of a kerb stone. In this way, obstacles in the direct vicinityof the edge of the kerb stone which constitute a real hazard whenparking can still be effectively detected while a pedestrian who isstanding on the sidewalk is outside the measuring range. The measuringdepth is preferably set automatically after a rear boundary of theparking space, for example the edge of a kerb stone, is sensed and itsdistance from the sensor system determined.

In one alternative embodiment of the method, instead of component imagesof the parking space a situation image of the entire parking space isrecorded with the sensor system. If the vehicle 2 stops, for exampledirectly next to the parking space 1, the 3-D sensor system can record athree-dimensional situation image of the parking space 1 (measuringrange 5 a, represented by dashed lines in FIG. 1) using a wide anglelens. In this context the 3-D sensor system supplies topographicalinformation about the existing parking space, that is to say informationabout the height, width and depth of the parking space 1 is senseddirectly by the sensor system. The situation image, and thetopographical image which is contained in it and which relates to theparking space, is then processed by the evaluation unit (notillustrated) in order to determine the dimensions of the free parkingspace and evaluate the suitability of the parking space for the vehicle2.

If the evaluation of the suitability of the parking space is detected,that is to say if the length and the depth of the parking space 1 permitparking, for example an optical or audible enabling signal can betransmitted to the driver of the vehicle 2.

FIG. 2 illustrates the propagation time method which can be used todetermine the depth of an image by means of a 3-D sensor system 8. Theperiod of time, illustrated by the stop watch, between the emission of alight pulse 9 and the reception of a reflected light pulse 10 isdetermined. This period of time is then converted into a distancebetween the 3-D sensor system and the reflected object. In addition tothe actual two-dimensional image information it is possible to use thismethod to simultaneously determine depth information for each pixel ofthe sensor system. In this way the topographical image of the parkingspace is produced.

FIG. 3 shows a block diagram of a 3-D sensor system 8. The lattercomprises essentially a lighting unit with a light source 12 and anassigned ballast device 14 as well as an image recording unit with animage sensor 16 with associated driver circuit 18. The light source ispreferably an infrared light source so that the light which is emittedby it is not disruptive to people.

The lighting unit and the image recording unit are connected to anelectronic control and evaluation device 20 which coordinates thefunctions of the two units and processes the recorded situation images.

LIST OF REFERENCE NUMERALS

-   1 Parking space-   2 Vehicle-   3 Parked vehicles-   4 Obstacles-   5, 5 a Measuring range of the sensor system-   6 Direction of travel of the vehicle 2-   7 Exterior mirror of the vehicle-   8 Sensor system-   9, 10 Light paths during propagation time measurement-   12 Light source-   14 Ballast device-   16 Image sensor-   18 Driver circuit-   20 Electronic control and evaluation device

1.-16. (canceled)
 17. A method for providing parking aid for a vehicle,comprising: recording of ambient data in an external area of a vehicle,calculation of dimensions of a specific area using the recorded ambientdata, and p1 evaluation of a suitability of the specific area as aparking space taking into account the calculated dimensions and known,vehicle-specific reference values, wherein the recording of ambient datacomprises recording three-dimensional images of surroundings by means ofan optical 3-D system.
 18. The method as claimed in claim 17, whereinsaid optical 3-D system comprises a 3-D camera.
 19. The method asclaimed in claim 17, wherein the recording of ambient data comprises therecording a situation image of the entire area of interest.
 20. Themethod as claimed in claim 17, wherein the recording of ambient datacomprises the successive recording of adjacent component images of thearea of interest.
 21. The method as claimed in claim 17, wherein atopographical image of the specific area is created on the basis of therecorded ambient data.
 22. The method as claimed in claim 17, wherein anobstacle in the specific region is detected on the basis of the recordedsurroundings.
 23. The method as claimed in claim 17, wherein a result ofthe evaluation step is signaled to a driver of the vehicle.
 24. Themethod as claimed in claim 17, wherein, in addition to the calculationof the dimensions of the specific area, the position of the specificarea with respect to the vehicle is determined on the basis of therecorded ambient data.
 25. The method as claimed in claim 24, whereinthe calculated dimensions and position of the specific area aretransmitted to a control system for an automatic parking system.
 26. Adevice for providing parking aid for a vehicle, comprising a sensordevice for recording ambient data in an external area of a vehicle, andan evaluation device for calculating dimensions of a specific area on abasis of the recorded ambient data and for evaluating a suitability ofthe specific area as a parking space on a basis of the calculateddimensions and known, vehicle-specific reference values, wherein thesensor device comprises an optical 3-D sensor system for recordingthree-dimensional images of surroundings.
 27. The device as claimed inclaim 26, wherein the optical 3-D system comprises a 3-D camera.
 28. Thedevice according to claim 26, wherein the evaluation circuit determinesthe dimensions of the specific area on the basis of a situation image ofthe entire area of interest.
 29. The device as claimed in claim 26,wherein the evaluation circuit determines the dimensions of the specificarea on the basis of a plurality of successively recorded componentimages of the area of interest, wherein the various component images arecorrelated with one another by way of a determined vehicle velocity. 30.The device as claimed in claim 26, wherein the sensor device operates inthe infrared range.
 31. The device as claimed in claim 26, wherein theevaluation device is coupled to an information system for outputting aresult of the evaluation step to a driver of the vehicle.
 32. The deviceas claimed in claim 26, wherein the evaluation unit has means fordetermining the position of the specific area with respect to thevehicle.
 33. The device as claimed in claim 31, wherein the evaluationdevice is coupled to a control system for an automatic parking system inorder to transmit dimension data and position data of the specific area.34. The device as claimed in claim 26, wherein the optical 3-D sensorsystem is mounted on the vehicle, in the external area of the vehicle.35. A method for providing parking aid for a vehicle, comprisingrecording of ambient data in an external area of a vehicle, calculationof dimensions of a specific area using the recorded ambient data, andevaluation of a suitability of the specific area as a parking spacetaking into account the calculated dimensions and known,vehicle-specific reference values, wherein the recording of ambient datacomprises recording three-dimensional images of surroundings by means ofan optical 3-D camera.
 36. The method as claimed in claim 35, whereinthe recording of ambient data comprises the recording a situation imageof the entire area of interest.
 37. The method as claimed in claim 35,wherein the recording of ambient data comprises the successive recordingof adjacent component images of the area of interest.
 38. The method asclaimed in claim 35, wherein a topographical image of the specific areais created on the basis of the recorded ambient data.
 39. The method asclaimed in claim 35, wherein an obstacle in the specific region isdetected on the basis of the recorded surroundings.
 40. The method asclaimed in claim 35, wherein a result of the evaluation step is signaledto a driver of the vehicle.
 41. The method as claimed in claim 35,wherein, in addition to the calculation of the dimensions of thespecific area, the position of the specific area with respect to thevehicle is determined on the basis of the recorded ambient data.
 42. Themethod as claimed in claim 41, wherein the calculated dimensions andposition of the specific area are transmitted to a control system for anautomatic parking system.
 43. A device for providing parking aid for avehicle, comprising a sensor device for recording ambient data in anexternal area of a vehicle, and an evaluation device for calculatingdimensions of a specific area on a basis of the recorded ambient dataand for evaluating a suitability of the specific area as a parking spaceon a basis of the calculated dimensions and known, vehicle-specificreference values, wherein the sensor device comprises an optical 3-Dcamera for recording three-dimensional images of surroundings.
 44. Thedevice according to claim 43, wherein the evaluation circuit determinesthe dimensions of the specific area on the basis of a situation image ofthe entire area of interest.
 45. The device as claimed in claim 43,wherein the evaluation circuit determines the dimensions of the specificarea on the basis of a plurality of successively recorded componentimages of the area of interest, wherein the various component images arecorrelated with one another by way of a determined vehicle velocity. 46.The device as claimed in claim 43, wherein the sensor device operates inthe infrared range.
 47. The device as claimed in claim 43, wherein theevaluation device is coupled to an information system for outputting aresult of the evaluation step to a driver of the vehicle.
 48. The deviceas claimed in claim 43, wherein the evaluation unit has means fordetermining the position of the specific area with respect to thevehicle.
 49. The device as claimed in claim 47, wherein the evaluationdevice is coupled to a control system for an automatic parking system inorder to transmit dimension data and position data of the specific area.50. The device as claimed in claim 43, wherein the optical 3-D sensorsystem is mounted on the vehicle, in the external area of the vehicle.